Lubricating oil composition



United States Patent 3,239,463 LUBRICATING OIL COMPOSITION Edwin C.Knowles, Poughkeepsie, N.Y., and Edward L. Kay, Akron, Ohio,assignors'to Texaco Inc, New York, N.Y., a corporation of Delaware NoDrawing. Filed Mar. 24, 1965, Ser. No. 442,472 6 Claims. (Cl. 252-331?)This application is a continuation-in-part of now abandoned applicationS.N. 83,182.

This invention relates to a lubricating oil composition characterized byhaving outstanding load-carrying properties. More specifically, theinvention relates to a lubricating oil containing a tertiary alkylprimary amine salt of a tetra-covalent boron acid.

Lubricating oil compositions containing certain 'organoboron compoundshave been formulated heretofore. Amine salts of acid compounds of boricacid and of borodiol complexes have been employed in lubricating oils toimprove resistance to sludge-formation and to improve anti-corrosionproperties, see US. Patent Nos. 2,497,521 and 2,568,472. Bora'te estershave also been employed in lubricating oils but their use has beenseriously hindered by their hydrolytic instability.

The present invention is concerned with lubricating oil compositionscontaining tertriary alkyl primary amine salts of tetra-covalent boronacids known as chelate type salts which are represented by the followinggeneral formulae:

wherein R is a monovalent tertiary aliphatic hydrocarbyl radical havingfrom to -24 carbon atoms, R is a divalent aryl or alkaryl radical having6 to 24 carbon atoms and R is a divalent aryl or alkaryl radical having6 to 24 carbon atoms or an aliphatic hydrocarbyl radical having 2 to 4carbon atoms. The acid-amine salt is present in the lubricating oil in aconcentration range from above 0.5 to 5.0 weight percent an amounteffective to impart load-carrying properties.

The amine salts for the present invention are prepared by the reactionof boric acid with a polyhydroxy compound or hydroxy carboxylic acid toform the tetra-covalent boron compound which is thereafter reacted witha tertiary aliphatic primary amine. The reaction mixture is diluted witha solvent such as toluene and heated to reflux temperature at normalatmospheric pressure. The solvents are then removed preferably byazeotropic distillation and the amine'salt recovered.

The amines employed in the formation of the salts of the chelatedtetra-covalent boron acid" are represented by the formula:

RNH

wherein R is a monovalent tertiary aliphatic hydrocarbyl radical having5 to 24 carbon atoms. Preferably R represents a tertiary aliphatichydrocarbyl radical having from 11 to 22 carbon atoms. Examples ofeffective tertiary aliphatic primary amines include t-octylamine,tdodecylamine, and mixtures of primary aliphatic amines such ascommercially available mixtures of t-alkyl primary amines. A commercialmixture of monovalent tertiary aliphatic hydrocarbyl amines having 11 to14 carbon "ice pounds and as such do not exist in the isolated state.

They do, however, form stable salts. The acids are formed by reacting'boric acid with a polyhydroxy compound or hydroxy carboxylic acid whichmay be illustrated by the following general equation:

wherein R is 'a divalent aryl or alkaryl radical having from 6 to 24carbon atoms.

The chelated tetra-covalent boron acids employed in the formation of theamine salts of the present invention can be represented by the followingformulae:

wherein R is a divalent aryl or alkaryl radical having 6 to 24 carbonatoms, preferably 6 to 12 carbon atoms, and R is a divalent aryl oralkaryl radical having 6 to 24 carbon atoms or an aliphatic hydrocarbylradical having 2 to 24 carbon atoms, preferably 4 to 18 carbon atoms.Examples of effective acids are boro catecholate acid, alkyl derivativesof boro resorcinate acid, boro salicylate acid, boro alpha hydroxydecanoate acid, boro beta hydroxy decanoate acid, boro glycolate acid,boro propylene glycolate acid, boro tetramethyl ethylene glycolate acidand boro oxalate acid.

Upon the formation of the transistory acids, described above the amineis reacted therewith to obtain the desired amine salt, the reaction forwhich may be illustrated by the following general equation:

wherein R is a monovalent tertiary alphatic hydrocarbyl radical having 5to 24 carbon atoms and R is a divalent aryl or alkaryl radical having 6to 24 carbon atoms.

The effective amine salts are illustrated by the following: t-C C alkylprimary amine boro catecholate, -t-C -C alkyl primary amine boroalkylcatecholate, LC -C alkyl primary amine boro resorcinolate, t-C Calkyl primary amine boro alkylresorcinolate, t-C C alkyl primary aminoboro salicylate, t-C C alkyl primary amine boro alkylsalicylate, ec -calkyl primary amine boro alpha hydroxy decanoate, t-C C alkyl primaryamine boro alpha hydroxy alkyldecanoate, ec -c alkyl primary amine boroglycolate, t-'C C alkyl primary amine boro propylene glycolate, t-C -Calkyl primary amine boro tetramethyl ethylene glycolate, ec -c alkylprimary amine boro oxalate, PC -C alkyl primary amine boro catecholate,FO -C alkyl primary amine boro alkylcatecholate, t-C -C alkyl primaryamine boro resorcinolate, t-C C alkyl primary amine boroalkylresorcinolate, t-C -C alkyl primary a amine boro salicylate, t-C Calkyl primary amine boro alkylsalicylate,t-C C alkyl primary amine boroalpha hydroxy decauoate, t-C C alkyl primary amine boro alpha hydroxyalkyldeconoate, t-Cm-C alkylprimary amine boro glycolate, PC alkylprimary amineboro propylene glycolate, vo -cs alkyl primary amine borotetramethyl ethylene glycolate, tC C alkyl primary amine boro oxalate,t-octyl amine boro catecholate, t-octyl amine boro alkylcatecholate,t-octyl amine boro resorcinolate, t-octyl amine boro alkylresorcinolate,t-octyl amine amine boro alpha hydroxy decanoate, t-octyl amine boroalpha hydroxy alkyl decanoate, t-octylamineboro gly'-.. colate, t-octylamine boro propylene glycolate, t-octyl;

amine boro tetramethyl ethylene glycolate, and t-octyl amine borooxalate.

The concentration of the tertiary alkyl primary amine salt of atetra-covalent boron acid of the invention in a lubricating oilcomposition is. critical. Generally,.a concentration ranging from above0.5 percent by weight to i from hydrocarbonsynthetic ilubricatingoilbases. The.

- hydrocarbon oils found, to be useful for this invention include oils.having a viscosity in the .rangerequired for lubricating fluids and inparticular hydrocarbon mineral oils which include parafiinzbase,naphthene base, mixed 1 paraflinnaphthenebase and mineraloilsiof theresidual or distillate type The hydrocarbon lubricating base gener- '10boro salicylate, t-octyl amine boro alkylsalicylate, t-octyl 5.0 percentby weight is essential to impart load carrying EXAMPLE I.-PREPARATION OFCHELATE AMINE BORO SALT OF SALICYLIC ACID 123.6 grams, 2.0 mols of boricacid, 552 grams 4.0

mols, sali cylic acid and 500 mls. of benzene were refluxed and theWater of the reaction removed by azeotropic distillation. Thereafter 400grams, 2.0 mols of a mixture oft-alkyl primary'amine wherein the t-alkylradical contains 11 to 14 carbon atoms .was added to the reactionmixture. The pot temperature rose from 75 C. to 85 C.

Q has been found eifective and are generally incorporatedAfter-stripping solvents to a pot temperature of 150 .C., 944 grams ofclear viscous t-C -C primary amine boro salicylate liquid were isolatedand at ambient tempera-- ture the reaction product solidified.

EXAMPLE II.PREPARATION OF 'CHELATE AMINE BORO SALT OF 'ALPHA-HYDROXYDECANOIC ACID 61.8 grams, 1.0 mol of boric acid, 200 mls..of toluene and376 grams, 2.0 mols, of alpha hydroxy decanoic acid were refluxed and 46mls. of water were removed by azeotropic distillation. The toluene wasstripped 'at "a pot temperature of 195 C. Uponthe addition of..195grams, 1.0 mols of amixture of t-alkyl primary amines 'wherein thet-alkyl groups contained 11 'to 14 carbon atoms mixture, the pottemperature rose from 50 C. to 92 C. 350 mls. of pentane were added tothe reaction mixture and the solution was filtered. Pentane was re-'moved by heating the product and 558 grams of-clear amber t-C -C primaryamine boro alpha hydroxw decanoate liquid were isolated.

EXAMPLE III.-PREPARATION OF CHELATE: AMINE BORO SALT OF CATECHOL" 61.8grams, 1.0 mol of boric acid, 220 grams, 2.0 mols of catechol and 200mls. of toluene were refluxed and 51 mols of water were isolated byazeotropic distillation. Solvents were strippedto a pot temperature of170 0.

Upon cooling to room temperature a solid separated.-

195 grams, 0.1 mol of a mixtureof t-alkyl primary amine wherein thet-alkyl groups contained 11 to, 14 carbon atoms mixture were added andthe pot temperature roseally has-been subjected to solvent refiningtoimprove its oxidation and thermal stability and viscosity-temperatureproperties asswell as solv'ent dewaxingto remove vwaxy components and.to improve the-pour. properties: of :the

oil. Broadly speaking,ihydrocarbon lubricating oils having anSUSviscosity at;l00 Fiof between-5010 :2500 are vus'edini'theiformulation'of the improved lubricants:

of this invention; V

The minerallubricating oils to designed to impart-desirableg: propertiesthereto. For example, viscosity, index improvers, such as the'polymeth-f acrylates having .a molecular weight ranging from 500 to25,000 are usually included .therein'.: The improver having thefollowing normally used is a polymethacrylate recurring structural unit:I

wherein R is an aliphaticradical ranging from'butyl to stearyl andxn isan integer of morethan -l.

The use of various metal? baseforganic type additives in the lubricatingoils of this invention, particularly those:

oils used in high speed, spark ignition and diesel engines to reducering. sticking, minimize carbon deposits.

lacquer. formation and- The hydrocarbon lubricating oils of thisinvention may:

also contain other additives such as metal ,sulfonatesto afiordadditional detergent-dispersant properties, metal,

dialkyl dithiophosphates to afford additional. corrosion and oxidationresistance, and anti-foam agents such as silicone polymers in the amountof'about 5 to. 200 parts per million, etc.

from 60 C. to 'C. A water bath was then used-to cool the mixture. Somesolids were still presentin the reaction mixture and thereafter 500 mls.of pentane were added. The mixture was filtered and stripped of pentane.391 grams of dark amber t-alkyl C C amine boro catecholate liquid wereisolated.

The lubricating oils of this invention are prepared,

The esters which constituted the synthetic lubricant composition of thisinvention are broadly described as;

They are. high esters "of hydrocarbyl carboxylic acids. molecularweight'materials of lubricating oil characteristics derived fromalcohols which are ;usually aliphatic; alcohols containing 1 or more,hydroxyl radicals and monocarboxylic acids which are usuallyaliphatic-canboxylic 'acids containing 1 or; more carboxylic acidradicals.

Widely used synthetic ester lubricants arealiphatic diesters ofaliphatic dicarboxylic acids containing 6 to 12 L carbonatoms. From thestandpoint of cost and availability, the preferred dibasic acidsrareadipic acid, sebacic acid and azelaic acid. The aliphatic-alcohols usedto form the diesters usually contain at :least 4 carbon atoms and up to20m more carbon atoms. C to C alcohols are most commonly used. Etheralcohols such as Cellosolve and Carbitol may also beused inthe formationof the aliphatic diesters of organic dicarboxylic acids used as thelubricating base in-the compositions ofthis invention. Alcoholscontaining 2 for more hydroxyl radicals and no hydrogen substituted: on;the beta carbon atom such as trimethylol. propane. and.pentaerythritolhave .proven particularly elfective in formulatingstable high temperature .ester lubricants.

Examples of alkyl esters-of aliphatic carboxylic. acids are thefollowing; difisooctyl .azelate, di-2-ethylhexyl.v sebacate,di-2-ethylhexy1 azelate, di-Z-ethylhexyl adipate,

dilauryl azelate, di-sec-amyl sebacate, di-2-ethylhexylalkenyl-succinate, di-Z-ethoxyethyl sebacate, di-2-(2,--

methoxy-ethoxy) ethyl Tsabacate, di-2- (2-ethylb;utoxy) ethyl sebacate,di-Z-butoxyethyl azelate, di-2-(2'-ibutoxywhich the amine salts of thisinvention are added usually contain other additives 7 ethoxy) ethylalkenyl-succinate, pentaerythritol tetracaproate and trimethylol propanetri-isooctanoate.

In addition to such esters, polyester lubricants formed by a reaction ofan aliphatic dicarboxylic acid, a dihydroxy compound and amonofunctional compound, which is either an aliphatic monohydroxyalcohol or an aliphatic monocarboxylic acid, in specified mol ratios arealso employed as the synthetic lubricating base in the compositions ofthis invention; polyesters of this type are described in U.S. 2,628,974on Polyester Synthetic Lubricants, which issued to R. T. Sanderson onFebruary 17, 1953. Polyesters formed by reaction of a mixture containingspecified amounts of 2-ethyl-1,3-hexanediol, sebacic acid, and2-ethylhexanol and by reaction of a mixture containing adipic acid,diethylene glycol and 2- ethylhexanoic acid illustrate this class ofsynthetic polyester lubricating bases.

The sulfur analogs of the above-described esters are also used in theformulation of the lubricating compositions of this invention.Dithioesters are exemplified by di-Z-ethylhexyl thiosebacate, di-n-octylthioadipate and the dilaurate of 1,5-pentanedithiol; sulfur analogs ofpolyesters are exemplified by the reaction product of adipic acid, thioglycol and 2-ethylhexyl mercaptan.

Alkyl-substituted phenols are usually incorporated in the lubricants ofthe invention as anti-oxidants. The preferred and most commonly usedalkyl phenol antioxidants is 2,6-di-tertiary octylphenol;2,6-di-tertiary amyl-4-methylphenol; and2,6-di-isopropyl-4-methylphenol. Hindered phenols of this type areemployed in concentrations between 0.1 and 1.0 weight percent.

Although hindered phenol type anti-oxidants are the most widely usedanti-oxidants in the lubricant compositions of the invention,aryl-substituted amine anti-oxidants such as phenylnaphthylamine,phenylene diamine, and diphenylamine are also used in lubricants inconjunction with the extreme pressure additive of the invention. Theamine anti-oxidants are employed in the same concentrations as thehindered phenol anti-oxidant.

Organic silicones are normally incorporated in the lubricants of theinvention to impart thereto anti-foam properties. The silicones areusually of the d-ialkyl or mixed alkyl-aryl silicone type. Dimethylsilicone is normally employed as the anti-foam agent. The silicone isincorporated in the lubricant by means of a kerosene concentratecontaining 5 to 15 weight percent silicone. A very satisfactoryanti-foam agent is a kerosene concentrate weight percent dimethylsilicone. The kerosene concentrate is employed in an amount sufiicientto provide a silicone polymer concentration of from 50 to 250 parts permillion based on the total lubricant composition.

To demonstrate the excellent improvement in the loadcarrying ability oflubricating oil containing the amine salts of the present invention,high speed gear scuff test was used. This test is called the LAB. GearTest and is intended for the evaluation of the load-carrying ability ofthe scuff limited load-carrying ability of those lubricants used inreduction and accessory drives of turbo-jet and turbo-prop engines. TheI.A.E. Gear Test is one of the requirements of the British specificationD.E.R.D. 2,487 Lubricating Oil, Aircraft Turbine Engine, Synthetic Type.The I.A.E. Gear Test is also designed to evaluate the scuti limited,load-carrying ability of aircraft gear hydrocarbon lubricants.

The results of the I.A.E. Gear Test on lubricating oil compositions ofthe present invention are set forth in the following tables:

Table 1.l.A.E. gear test Oil:

Base oil B consisted of a paraffin base crude which has been furfuralrefined, lightly acid treated, clay contacted and solvent dewaxed andhas an SUS viscosity at F. of 150.

The criticality in the concentration of the additive as well as theload-carrying properties of a synthetic lubricating oil composition aredemonstrated by the results given in Table II. Base oil C, which wasemployed in these tests, was di-Z-ethyl hexylsebacate, a synthetic oilof lubricating viscosity.

Table II.I.A.E. gear test Tooth loadpounds Blend: 2000 sl'bglg. testBase oil C 50,60 Base oil C plus 0.1% PO -C primary amine'borosalicylate 50 Base oil C plus 0.25% ec -c primary borosalicylate 60Base oil C plus 0.5% EC -C primary amine borosalicylate 80 Base oil Cplus 2.0% tC C primary amine borosalicylate The foregoing results showthat significant load-carrying properties begin when the concentrationof the additive is above 0.5 percent by weight, lesser amounts of theadditive producing no improvement in load-carrying properties over thoseof the base oil itself.

In addition to the load-carrying properties, the amine salts of thechelated tetra-covalent boron acids of the invention also impart a highdegree of oxidation and corrosion resistance to lubricating oilcompositions. Many organo borate compounds do not perform assatisfactory additives for lubricants because of their hydrolyticinstability. In this respect, the salts of the present invention haveanother improtant advantage, namely that the amine salts of the chelatedtetra-covalent boron acids are hydrolytical'ly stable in both water andlubricating oils.

We claim:

1. A lubricating oil containing above 0.5 to 5 percent by weight of anamine salt of a tetra-covalent boron acid, said amine salt having theformula:

wherein R isa monovalent tertiary aliphatic hydrocarbyl radical havingfrom 5 to 24 carbon atoms and R" is selected from the group consistingof divalent aryl and alkaryl radicals having from 6 to 24 carbon atoms.

2. A lubricating oil as described in claim 1 wherein R is a mixture ofmonovalent tertiary aliphatic hydrocarbyl radicals having from 11 to 14carbon atoms.

3. A lubricating oil as described in claim 1 wherein R is a mixture ofmonovalent tertiary aliphatic hydrocarbyl radicals having from 18 to 22carbon atoms.

4. A lubricating oil composition according to claim 1 in which saidamine salt is present in a concentration of from 0.6 to 2.0 weightpercent.

5. A lubricating oil as described in claim 1 containing above 0.5 to 5.0weight percent of an amine salt having the formula:

HRNH:

wherein R is a mixture of tertiary alkyl groups having from 11 to 14carbon atoms.

vwherein R is a mixture of tertiary alkyl groupsbhaving 6.: Alubricating oil as described in claim 1 containing: I References (literdby the rExaminer."v

above 0.5 to 5.0 weight percent of an amine'sa'lt having I "UNITED -1. P

from 11 to 14 carbon atoms.

1. A LUBRICATING OIL CONTAINING ABOVE 0.5 TO 5 JPERCENT BY WEIGHT OF ANAMINE SALT OF A TETRA-COVALENT BORON ACID, SAID AMINE SALT HAVING THEFORMULA: